The invention discloses a reinforcing steel bar hoop-bending machine which comprises a rack, a straightening mechanism, a drawing mechanism, a shut-off mechanism and a return bending mechanism, wherein the straightening mechanism, the drawing mechanism, the shut-off mechanism, and the return bending mechanism are connected in sequence from front to back. The mechanization of the whole loop bending of reinforcing steel bars is realized by the return bending mechanism provided by the invention, the loop bending speed is accelerated, and workers are emancipated from heavy physical labor, thus the loop bending speed is accelerated, and the work efficiency is improved.